CRP-RF-Wright_and_coombs_wight

Introduction

  • In the Name of God

Institutional Affiliation

  • Tehran University of Medical Sciences

  • Department of Immunology, School of Medicine

  • CRP, RF, Wright, and 2ME/Coombs Wright test

  • Author: T Soltantoye

Antigens and Antibodies

  • Definitions:

    • Antigen: Any substance that can provoke an immune response.

    • Antibody: A protein produced by plasma cells that specifically binds to an antigen.

  • Detection Methods:

    • Visible and in-visible detection (.e.g., colored reactions visible to the naked eye versus requiring special equipment).

    • Detection methods include:

      • Agglutination

        • Clumping of particles; tests for the presence of antibodies or antigens.

      • Precipitation

        • The formation of a solid in a solution during a reaction.

      • Immunoassays

        • Techniques using antibodies to detect substances in a sample, e.g., colorimetric, fluorescence, radioactivity, etc.

Visible Antigen-Antibody Complexes

  • Differences and Similarities:

    • Antibodies cross-link antigens to form Ag-Ab lattices.

    • Precipitation: Involves soluble antigens.

    • Agglutination: Involves insoluble antigens.

Types of Agglutination

  • Categories:

    • Hemagglutination: Agglutination of red blood cells.

    • Various reactions include:

      • Direct: Detecting antigens directly in the sample.

      • Passive: Using a carrier for antigen detection.

      • Reverse passive: Detect antigens using antibodies adsorbed to carriers.

Brucellosis Overview

  • Definition: Zoonotic disease, also known as:

    • Undulant fever

    • Malta fever

    • Mediterranean fever

  • Pathogen: Brucella: Gram-negative, small, coccobacilli, non-motile, non-capsulated.

Wright Test

  • Component of testing for Brucellosis

  • Rose Bengal Test: Utilizes a specific reagent and patient serum to confirm the presence of Brucella.

Agglutination Testing Methods

  • Standard Tube Agglutination Test:

    • Procedure involves transferring serum samples and diluting with saline.

    • Serial dilutions indicated (e.g., 1:20, 1:40, etc.) in test tubes.

Titer Determination

  • Interpretation:

    • Control and test results indicate levels of antibodies.

    • Maximum dilution showing agglutination designates the titer (e.g., 1/640).

False Negative Results

  • Possible outcomes:

    • Occurs when blood culture is positive while the Wright test is negative

    • Likely causes include blocking antibodies and differences in antigen or antibody concentrations.

Antiglobulin Reaction

  • Tests involving Anti-IgG antibodies can indicate agglutination response.

2ME-Wright Test

  • Differentiates between IgM and IgG antibodies.

  • Aids in confirming chronic or acute infections by assessing antibody titer reductions.

Passive Agglutination Techniques

  • Inert carriers like latex particles and carbon particles used in tests for specific antibodies.

  • Used in the ASO (Anti-Streptolysin O) test among others.

Rheumatoid Factor (RF)

  • Definition: Antigen related to rheumatoid arthritis (RA).

  • Mechanism:

    • B-Lymphocyte activation leading to Plasma cell production of IgM.

    • IgM attacks IgG (anti-IgG) indicating RA.

Latex Tests for Rheumatoid Factor

  • RA Latex Test: Utilizing latex particles coated with IgG to detect patient serum RF (IgM).

Reverse Passive Agglutination

  • Antibodies immunoadsorbed onto carrier particles to facilitate antigen detection (e.g., CRP).

C-Reactive Protein (CRP)

  • Definition: Acute phase protein involved in the body's inflammatory response.

  • Key diagnostic tool for both infections and inflammation.